1. Field of the Invention
The present invention relates to a piezoelectric ceramic composition, a piezoelectric element, and a resonator.
2. Related Background Art
Piezoelectric ceramic compositions have both of a piezoelectric effect for causing electric polarization in response to a pressure from the outside and an inverse piezoelectric effect for generating distortion in response to an electric field applied thereto from the outside, and thus are employed as a material for performing interconversion between electric and mechanical energies. Such piezoelectric ceramic compositions have been in use in a wide variety of products such as resonators, filters, sensors, actuators, ignition devices, and ultrasonic motors (see Japanese Patent Application Laid-Open No 2000-1367).
Characteristics of such piezoelectric ceramic compositions have been improved by adding various accessory components to perovskite-type oxides based on PZT (PbTiO3—PbZrO3 solid solution) or PT (PbTiO3). For example, Japanese Patent Application Laid-Open No. 2000-1367 proposes to improve the temperature characteristic of resonance frequency by adding Nb2O5 and MnO2 to a perovskite-type oxide based on PbTiO3.